#include <Wire.h>
#include <LiquidCrystal_I2C.h>

#define trigPin 9
#define echoPin 8
#define buzzerPin 10
#define ledAlertPin 11
#define ledClearPin 12

// Initialize the LCD
LiquidCrystal_I2C lcd(0x27, 16, 2);  // Address 0x27, 16 chars, 2 rows

long duration;
int distance;

// Number of readings to average
const int numReadings = 5;

// Timer variables
unsigned long detectionStartTime = 0; // Time when vehicle is detected
bool vehicleDetected = false; // Flag to check vehicle detection

void setup() {
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(buzzerPin, OUTPUT);
  pinMode(ledAlertPin, OUTPUT);
  pinMode(ledClearPin, OUTPUT);
  Serial.begin(9600);
  
  // Initialize the LCD
  lcd.init();
  lcd.backlight();  // Turn on the backlight
  lcd.setCursor(0, 0);
  lcd.print("Parking System");
  delay(2000);  // Display the message for 2 seconds
  lcd.clear();
}

int getAverageDistance() {
  long totalDistance = 0;
  for (int i = 0; i < numReadings; i++) {
    // Clear the trigPin
    digitalWrite(trigPin, LOW);
    delayMicroseconds(2);

    // Set the trigPin high for 10 microseconds
    digitalWrite(trigPin, HIGH);
    delayMicroseconds(10);
    digitalWrite(trigPin, LOW);

    // Read the echoPin and calculate the distance
    duration = pulseIn(echoPin, HIGH);
    int currentDistance = duration * 0.034 / 2;
    totalDistance += currentDistance;

    delay(50);  // Delay between readings
  }
  return totalDistance / numReadings;  // Return the average distance
}

void loop() {
  // Get the average distance
  distance = getAverageDistance();

  // Display the distance on the LCD
  lcd.setCursor(0, 0);
  lcd.print("Distance: ");
  lcd.print(distance);
  lcd.print(" cm   ");  // Clear remaining characters

  // Check if a vehicle is detected
  if (distance < 100 && distance > 0) { // Vehicle detected
    if (!vehicleDetected) {
      vehicleDetected = true;
      detectionStartTime = millis(); // Record the time of detection
    }
    
    // Check if 30 seconds have passed since vehicle detection
    if (millis() - detectionStartTime >= 30000) { // 30 seconds
      tone(buzzerPin, 1000);  // Produce continuous beep at 1000 Hz
      digitalWrite(ledAlertPin, HIGH);
      digitalWrite(ledClearPin, LOW);
      
      // Display alert message on the LCD
      lcd.setCursor(0, 1);  // Move to second row
      lcd.print("Vehicle Detected");
    }
  } else {
    // If no vehicle is detected
    vehicleDetected = false; // Reset the vehicle detection flag
    noTone(buzzerPin);  // Stop the beep
    digitalWrite(ledAlertPin, LOW);
    digitalWrite(ledClearPin, HIGH);
    
    // Display clear road message on the LCD
    lcd.setCursor(0, 1);
    lcd.print("Road is Clear   ");  // Clear remaining characters
  }

  delay(500);  // Delay for half a second
}